I live in Tucson, so I know about harsh summers, lost a few fish last year because of the temp change I would get in a day. We get the setting sun, it's hot! But we bought a shade for our porch and that's helped cool down the wall our tank is against. And as these other guys have said, my hood has 2 small fans from Radio Shack and they've helped me keep an almost constant 75-77 degrees.
King